A lot of such research has been done in media studies - what they usually find is no direct effect. The effect that has been confirmed as "agenda setting" (i.e. media not telling you what to think but what to think about). Another outcome is the "uses gratifications" which emphasizes the fact that media contents is usually socially mediated and interpreted and as such beyond control of the original sender. In other words, any message is usually re-constructed, re-interpreted and integrated into larger interpretative frames by the audience and that process is affected by local social norms, values, expectations etc. As a result the effect intended by the original sender is often diluted, altered or altogether lost.
While we are at that, my original master thesis idea involved an experimental research to test the hypothesized "learned helplessness" effect induced by the media. In psychology, learned helplessness denotes a situation in which repeated administration of aversive stimuli to "experimental" subjects (they've done with both animals and people) produces the absence of avoidance behavior to such stimuli in the future, together with other negative effects, such as depression and the impaired learning ability. I hypothesized that the media form (constant commercial interruptions) and contents (violence and gore) produce such learned helplessness, and I proposed an experimental design to measure it by pre- and post- learning tests. My advisor persuaded me not to pursue that project, arguing that most likely I would not get any measurable results.
>
> Now, are people persuaded by art? W, you have
> practically the entire weight of Western though
> against you -- high and low. That's why Plato wanted
I did not say that art has no influence, all I was saying that it is difficult to use art as a tool to achieve an effect that is desirable from a broadly defined left point of view. More specifically, I was objecting to the proposition of using shock in art as the means to influence people.
That art does influence people can be easily demonstrated by marketing and advertisement - which is an art form of a sort and clearly does influence people. But marketing also tells us that the most persuasive messages are certainly not the ones that are shocking and repulsive.
The ubiquitous and frivolous use of violence in pop-culture is a result of several factors, such as the mass media creating what amount to "background noise" which in turn creates the need for attention grabbing artifices for individual messages to stand out from that cacophony, or the manufacturing of the "teenage counter-culture" that overstimulates dulled or unrefined tastes which was originally a niche that, like athletic shoes, swallowed the entire industry. That prevalence of overstimulation and attention grabbing in popculture, of which sex and violence are critical parts because we are biologically pre-wired to pay attention to this kind of stimuli all but killed any potential artistic value of sexual or violent contents (cf. Dali).
As a result, I avoid any message that contains depictions of violence - even those in "lefty" publications intended to create moral outrage - because such messages only make me upset and obscure rational thinking. The only effect of these messages is to make me inclined to avoid the subject altogether rather than trying to do something about it - which was supposed intention of the message.
I also avoid any form of "in-your-face" message or artistic form. Part of it is because of the ubiquity and overstimulation mentioned earlier, and another part of it is that it epitomizes the "me-centrism" forming the backbone of the consumer society - everything centers around ME so I can do whatever it takes to get what I want and stick it in your face if I need to and I do not really give a shit whether anyone likes it or not and how it affects everyone else as long is it serves ME.
But that is, of course, different form claiming that art has no influence. However, that influence is usually different from that originally intended (the uses and gratifications effect) and its reception has cognitive limitations mentioned in my earlier posting.
Wojtek